—You didn't wait for Mr. Smith last night did you?—Yes but we . He didn't return home at

问题补充：

—You didn wait for Mr. Smith last night, did you?

—Yes, but we . He didn return home at all.

A. don have to

B. needn have

C. didn need to

D. should have

答案：

A. don have to

(答案→)B. needn have

C. didn need to

D. should have

解析：考查虚拟语气。句意：—昨天晚上你没有等斯密斯先生，是吗？—不，我等他了。但是我们本没有必要等他的。他根本没有回来。Need not have done sth本不需要做某事，实际上却做了。故B正确。